/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements. See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You under the Apache license, Version 2.0
    * (the "License"); you may not use this file except in compliance with
    * the License. You may obtain a copy of the License at
    *
    *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the license for the specific language governing permissions and
   * limitations under the license.
   */
  package org.apache.logging.log4j.web;
  // Please note that if you move this class, make sure to update the Interpolator class (if still applicable) or remove
  // this comment if no longer relevant
  
  import javax.servlet.ServletContext;
  
  import org.apache.logging.log4j.LogManager;
  import org.apache.logging.log4j.core.LogEvent;
  import org.apache.logging.log4j.core.LoggerContext;
  import org.apache.logging.log4j.core.config.plugins.Plugin;
  import org.apache.logging.log4j.core.impl.ContextAnchor;
  import org.apache.logging.log4j.core.lookup.StrLookup;
  
  
  @Plugin(name = "web", category = "Lookup")
  public class WebLookup implements StrLookup {
      private static final String ATTR_PREFIX = "attr.";
      private static final String INIT_PARAM_PREFIX = "initParam.";
  
      protected ServletContext getServletContext() {
          LoggerContext lc = ContextAnchor.THREAD_CONTEXT.get();
          if (lc == null) {
              lc = (LoggerContext) LogManager.getContext(false);
          }
          if (lc != null) {
              final Object obj = lc.getExternalContext();
              return obj != null && obj instanceof ServletContext ? (ServletContext) obj : null;
          }
          return null;
      }
  
      @Override
      public String lookup(final String key) {
          final ServletContext ctx = getServletContext();
          if (ctx == null) {
              return null;
          }
  
          if (key.startsWith(ATTR_PREFIX)) {
              final String attrName = key.substring(ATTR_PREFIX.length());
              final Object attrValue = ctx.getAttribute(attrName);
              return attrValue == null ? null : attrValue.toString();
          }
  
          if (key.startsWith(INIT_PARAM_PREFIX)) {
              final String paramName = key.substring(INIT_PARAM_PREFIX.length());
              return ctx.getInitParameter(paramName);
          }
  
          if ("rootDir".equals(key)) {
              final String root = ctx.getRealPath("/");
              if (root == null) {
                  final String msg = "Failed to resolve web:rootDir -- " +
                          "servlet container unable to translate virtual path " +
                          " to real path (probably not deployed as exploded";
                  throw new IllegalStateException(msg);
              }
              return root;
          }
  
          if ("contextPath".equals(key)) {
              return ctx.getContextPath();
          }
  
          if ("servletContextName".equals(key)) {
              return ctx.getServletContextName();
          }
  
          if ("serverInfo".equals(key)) {
              return ctx.getServerInfo();
          }
  
          if ("effectiveMajorVersion".equals(key)) {
              return String.valueOf(ctx.getEffectiveMajorVersion());
          }
  
          if ("effectiveMinorVersion".equals(key)) {
              return String.valueOf(ctx.getEffectiveMinorVersion());
          }
  
          if ("majorVersion".equals(key)) {
              return String.valueOf(ctx.getMajorVersion());
          }
 
         if ("minorVersion".equals(key)) {
             return String.valueOf(ctx.getMinorVersion());
         }
 
         if (ctx.getAttribute(key) != null) {
             return ctx.getAttribute(key).toString();
         }
 
         if (ctx.getInitParameter(key) != null) {
             return ctx.getInitParameter(key);
         }
 
         ctx.log(getClass().getName() + " unable to resolve key '" + key + '\'');
         return null;
     }
 
     @Override
     public String lookup(final LogEvent event, final String key) {
         return lookup(key);
     }
 }